CY
260
MB
CY
MB
Research Article
Potential diagnostic role of renal scintigraphy in the management of patients with high anorectal malformation
Abstract
Chidambaram Natrajan Balasubramanian Harisankar1 MBBS, Bhagwant Rai Mittal1 MD; DNB Anish Bhattacharya1 DNB;DRM Hejjaji Venkataramarao Sunil1 MD Baljinder Singh1 MSc; PhD Katragadda Lakshmi Narasimha Rao2 MS, MCh 1. Department of Nuclear Medicine 2. Department of Pediatric Surgery Postgraduate Institute of Medical Education and Research, Chandigarh, 160 012, India ✬✬✬
Keywords: Anorectal malformation – Renal anomalies -Scintigraphy – 99mTc-DTPA – 99mTc-DMSA
Correspondence address: Dr. B.R. Mittal, Prof. and Head, Department of Nuclear Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, 160 012, India Τel.: +91 172 275 6722 Fax: +91 172 2744401 E-mail:
[email protected] Received: 23 September 2009 Accepted revised: 30 October 2009
260
CY
Urological problems are the leading associated anomalies in patients with anorectal malformation (ARM). In this study, we evaluated the role of scintigraphy in managing patients with high ARM. The records of infants with urologic anomalies on abdominal ultrasound and referred for scintigraphic evaluation were retrospectively analyzed. Diuretic renography in these patients was performed using 99mTc-diethyl triamine penta-acetic acid (99mTc-DTPA) or 99mTc-ethylene cysteine (99mTc-EC) while cortical scintigraphy was performed with 99mTc-dimercaptosuccinate (DMSA). Whenever available, EC was preferred in children of age less than 1 year. Forty patients (38 males, 2 females) were analyzed. The mean age of the population was 25 months (range 15 days-21 years). Eighteen of the forty patients were less than 3 months of age. Twenty seven of the patients were less than one year of age. The most common renal anomaly was unilaterally non-visualized kidney affecting 15 out of the 40 patients. The visualised kidney was abnormal in 8/15 patients. Hydronephrotic changes were noticed in 12 of 40 patients of whom 2 had pelvi ureteric junction obstruction that was confirmed and treated surgically. Horse shoe kidney was present in 1 patient while 2 had an ectopic kidney. Scarring/ pyelonephritic changes were found in 7/40 patients. Five patients had already progressed to chronic renal failure at the time of scintigraphy. Only 8 patients of the 40 had bilaterally normal kidneys. In conclusion, this study suggests that urologic abnormalities often found in infants with high ARM may remain clinically silent and eventually lead to chronic renal failure. Proper evaluation by diuretic renography and cortical scintigraphy can lead to early identification of potentially treatable conditions hence reducing the likelihood of developing severe renal damage.
Hell J Nucl Med 2009; 12(3) : 260-265 • Published on line: 14 November 2009
Introduction
A
norectal malformation (ARM) is a developmental anomaly characterized by an absent or ectopic anus. It comprises a wide spectrum of disorders and involves the distal anus and rectum as well as the urinary and genital tracts. It affects children of both sexes and occurs in approximately 1 in 1500 to 5000 live births [1, 2]. Defects range from the very minor and easily treated with an excellent functional prognosis, to those that are complex, difficult to manage, often associated with other anomalies, and having a poor functional prognosis. Malformations of other organ systems have been reported with an incidence varying from 30% to 70% with some being life threatening [3-8]. Though various organ systems can be affected, the genitourinary, cardiovascular, gastrointestinal and vertebral systems are the four most commonly involved in this group of patients. Urological anomalies are the leading abnormalities associated with ARM [8]. Urinary anomalies are observed up to 50%-60% of patients with high or intermediate forms and 15%-20% of low ARM [9]. Unlike genital anomalies, urologic anomalies are difficult to identify on clinical examination and form the primary cause of morbidity and mortality [10]. An abdominal ultrasound (USG) is a relatively cheap and first line investigation for identification of urological anomalies. However, it is a relatively non-specific investigation. Renal scintigraphy is a highly sensitive investigation for the evaluation of renal function. However, role of scintigraphy in patients with ARMs is not clearly defined in the literature. In a recent study, urologic anomalies were identified in about 11% of the patients who underwent scintigraphic evaluation [11]. This study was undertaken to evaluate the role of scintigraphy in managing patients with high ARM.
Hellenic Journal of Nuclear Medicine • September - December 2009
MB
www.nuclmed.gr
CY
MB
CY
261
MB
CY
MB
Research Article
Subjects and methods This study included a retrospective analysis of records of all the patients with high ARM referred to our department from the period of January 2005 to November 2008. The records of 40 patients were analyzed. Their mean age was 25 months (range 15 days to 250 months). Eighteen of the patients were less than 3 months old, while 27/40 patients were less than 1 year old. All patients included had already undergone corrective surgery for anorectal malformation. Patients with renal abnormalities on USG were referred to our nuclear medicine department for scintigraphic evaluation. A specific investigation like micturating cystourethrography (MCUG) was performed on patients with hydroureteronephrosis on abdominal USG or with evidence of repeated urinary tract infection (UTI). Patients who developed UTI were also referred for renal scintigraphy. Scintigraphic evaluation of all 40 patients included both dynamic renography and cortical scintigraphy (24 of 40 patients). A total of 57 scans were performed in these 40 patients. These scans included technetium-99m diethyl triamine penta-acetic acid (99mTc-DTPA), 99mTc-ethylene cysteine (99mTc-EC) and 99mTc-DMSA cortical scintigraphy as indicated in Table 1. Whenever available, dynamic study using 99mTc-EC was preferred in children less than one year of age. Renal cortical scintigraphy was performed using 99mTc-DMSA. Followup renal scans were also performed in patients with pyelonephritic changes and in those with equivocal drainage. Seven patients with pyelonephritic changes/ cortical scars in either of the kidneys had repeat 99mTc-DMSA study. Ten patients had repeat dynamic renography. Of these patients, 2 had surgically proven pelvic-ureteric junction obstruction and repeat imaging was used to confirm the improvement in renal drainage. In the other 8 patients, repeated imaging was used for follow up of hydronephrotic change in either kidney. The patients were adequately hydrated by breast feeding and/or oral fluids as appropriate for their age. No intravenous rehydration was given. Babies younger than 5 months were not
given any sedatives. Patients of age 5 months to 5 years were sedated orally with syrup triclofos in a dose of 75-100mg/kg body weight. Diuretic was administered along with the radiotracer in all patients above 3 months of age in a dose of 1mg/kg. Perfusion images were obtained at 2sec/frame for the initial 1min and parenchymal images were acquired at 1min/frame for the next 24min. Post void images and delayed images up to 3h were acquired after keeping the baby upright for at least 3min to assist gravity dependent drainage in this age group. Persistent retention of tracer in the renal pelvis till 3h was labeled as indication of an obstructed urinary system. Cortical scintigraphy with 99mTc-DMSA included planar and pinhole images acquired 3h after tracer injection. Reduced tracer uptake without a break in cortical outline in patients with clinical evidence of UTI was considered indicative of a pyelonephritic change. A break in the cortical outline, especially when persistent on the follow-up scan, was labeled as scarring. Increased background tracer activity with poor cortical uptake was considered as compromised function. Unilateral relative renal function of less than 30% as compared to the other kidney was considered as impaired function.
Results Data analysis of the 40 patients (80 renal units or locations) showed 31 renal units (38.75%) to be structurally and functionally normal. This included 16 units in 8 patients and 15 units in 15 other patients (1 kidney in each patient). The other kidney was either non-visualized or had some functional abnormality in these 15 patients. Figure 1 shows renal function evaluated with 99mTc-DTPA and 99mTc-DMSA in one of our patients (Table 1). The most common renal anomaly was unilaterally nonvisualized kidney in 15 out of the 40 patients (37.5%). The contralateral solitary kidney in 7 of these 15 patients was normal. Among the remaining 8 patients (8 renal units), 3 had
Figure 1. (A): Diuretic renal scintigraphy using 99m Tc-DTPA. Left kidney shows good perfusion and cortical tracer uptake followed by unobstructed drainage. (B): 99m Tc-DMSA renal cortical scintigraphy reveals grossly increased background tracer activity. Severely impaired tracer uptake by both kidneys is noted suggesting bilateral severely impaired renal function.
www.nuclmed.gr
CY
MB
Hellenic Journal of Nuclear Medicine • September - December 2009
CY
261
MB
CY
262
MB
CY
MB
Research Article
Table 1. The imaging performed in every patient and their results. Data on MCUG were not available for all the patients Patient
Age DTPA / Repeat Sex DMSA (months) EC study
Left Kidney
Right Kidney
USG
No
RRF
